Relieving attachment for machine tools



Dec. 7, 1943.

E. A. WALKER RELIEVING ATTACHMENT FOR MACHINE TOOLS Filed Aug. 20, 1942 .om. w r--.

Patented Dec. 7, 1943 OLS Ernest A. Walker, Worcester, Mass., assignor to John Bath & Company, Worcester, Mass., at

corporation of Massachusetts Application August 20, 1942, Serial No. 455,492 3 Claims. (CI. 51-33) This invention relates to lathes and grinding machines or other machine tools which are used in cutting or grinding the teeth of taps or for other similar operations.

In the manufacture of taps or similar articles,

, it is customary to relieve the cut or ground surfaces for clearance by periodically reducing the distance between the cutting tool or grinding wheel and the work. This reduction in distance is very slight, commonly not over one or two thousandths of an inch. This introduces a serious problem of lubrication, as the coacting bearing surfaces do not have enough relative movement to efiectively distribute lubricant between the engaging surfaces.

My present invention relates more specifically to machines in which the tool supporting head or grinding wheel head is moved relative to the work.

It is the general object of my invention to provide an improved supporting structure for the tool head or grinding wheel head, by which slight oscillatory movements for relief or clearance may take place without relative movements of engaging bearing surfaces.

To the accomplishment of this general object, I provide a relatively thick but slightly flexible supporting member, one part of which is clamped to a fixed support and another part of which is clamped to the tool head or grinding wheel head which receives the slight oscillatory clearonce or relieving movements. These slight relative movements are accomplished by slight flexing only of the supporting member.

My invention further relates to arrangements and combinations of parts which will be hereinafter described and more particularly pointed out in the appended claims.

A preferred form of the invention is shown in the drawing, in which Fig. 1 is a front elevation of a portion of a grinding wheel head embodying my improvements;

Fig. 2 is a side elevation, looking in the direction of the arrow 2 in Fig. 1; and

Fig. 3 is an enlarged partial sectional side elevation, taken along the line 33 in Fig. 1.

Referring to the drawing, I have shown a portion of a wheel head support I which may be mounted for movement either longitudinally or transversely in the machine or which may be held in fixed position while the work is moved relative thereto.

For the purposes of this application it may be understood that the wheel head support I0 is lieving of the teeth of the tap T.

fixed transversely during the grinding and re- The grinding wheel W is mounted on a spindle l2 rotatable in bearings in a wheel head I4. The wheel may be rotated in any convenient manner, as by a pulley l6 and belt H. A lug I 8 (Fig. 2) on the wheel head l4 is'normallyheld inengagement with a corresponding-lug IS on the wheel head support ill by the pull of the belt IT.

The special-means provided for movably securing the wheel head on the wheel head support will be hereinafter described.

The means for producing oscillatory relief or clearance movements comprises a cam 20 mounted on a shaft 2| rotatable in bearing brackets 22 projecting forward from the wheel head support ID. The shaft 2| extends through an opening 25 in a downward projection 26 of the wheel head l4, and the cam 20 is mounted in said recess.

A shoe 30 is slidably mounted in a recess 3| in the part 26 and is positioned in said recess by a screw 32 and lock nut 33. A lug 35 on the cam 20 engages the shoe 30 as the cam is oscillated. A follower 40 (Fig. 3) is slidable in a recess 4| in the extension 26 and is yieldingly forced toward the cam 20 by a spring 43 seated against a screw or stud 44. The follower 40 takes up all back lash between the cam 20, the shoe 30, and the extension 26 of the wheel head [4.

An arm 50 is mounted at one end of the shaft 2| and is provided with a cam roll 52 engaged by a cam 53 mounted on a shaft 54 rotatable in bearings fixed relative to the wheel head support l0. As the cam 53 rotates, the arm 50 receives clockwise swinging movements as viewed in Fig. 2, thus causing the lug 35 to engage the shoe 30 and swing the wheel head l4 and the wheel W very slightly toward the tap T, such movement being indicated with much exaggeration by the dotted line a in Fig. 2.

The cam shaft 54 is suitably connected for rotation in predetermined ratio to the rotation of the tap T. Where the cam has as many lobes as the tap has lands, as shown herein, the cam and the tap are to be rotated at the same speed.

In order to permit the slight relieving movements of the wheel head l4 caused by rotation of the cam 53, I provide a supporting member in the form of a flat steel plate which is of substantial thickness but of slight flexibility.

The upper portion of the plate 60 is clamped against a shoulder 6| in the wheel head support III by a clamping bar 62 and a plurality of clamping screws 63. The lower edge portion of the plate 60 is similarly secured against a shoulder 65 in the wheel head M by a clamping bar however, produce only a very slight flexing of the steel plate 60, and produce no relative movements of engaging bearing parts. Conseqi cniily lug about the axisof said shaft and swinging the tool head. toward the work to relieve the no problem of lubrication arises, which is of verysubstantial advantage over the best previous practice known to the applicant.

In the claims, the term tool is tobe underl e i5;

stood as including both cutting and grinding instrumentalities. 1 r 7 Having thus described my invention and the advantages thereof, I do not wish to be limited:

to the detailsv herein disclosed, otherwise than 20 as set forth in the claims, but what I claim is:

1. In a machine tool, a tool head, a tool head support, a rigidly secured but slightly flexible connection between said tool head and said support from which said tool head depends, a cam 25 mounted in fixed bearings and effective to swing said tool head on said flexible connection torelieve. the work, means to normally position said tool head, an abutment on said tool head engaged. by said cam to relieve the work, means to 30 7 change the position of said abutment in said tool head to predetermine the lost motion between said abutment and cam, and automatic means to oscillate said cam.

2. In a machine tool, a tool head, a tool head support, a rigidly secured but slightly flexible connection between said tool head andsaid support, a cam having a lug engaging said tool head, a shaft for said cam, an arm on said shaft, and a rotated cam periodically engaging said arm and thereby oscillating said first cam and cam work. a t

3. In a machinetool, a tool head, a tool head support; a'relatively firm but slightly flexible supporting connection between said head and said support and from which said tool head depends,

. an'actuator for said tool head, stops mounted on said tool head and engaging said actuator on opposite sides-thereof and thereby defining operative positions for said tool head, yielding means associated with one of said stops and effecting firm engagement of said stopswith said actuator, and means to move said actuator and to thereby ive said tool head periodic swinging movements on said connection and toward the work to relieve the work.

ERNEST A; WALKER. 

